Variable geometry compressors are finding increasing use for enhancing performance of internal combustion engines. Such compressors are typically driven via an exhaust turbine, which may be a fixed geometry exhaust turbine or a variable geometry exhaust turbine. Variable geometry compressors help to enhance engine performance by providing an ability to change an otherwise fixed diffuser geometry. For example, diffuser geometry may be changed to adapt the compressor map to the engine running conditions.
However, control strategies for variable geometry compressors are lacking. Only simple control strategies have been used such as changing the geometry in “steps” to avoid surge and choke, where the steps were manually determined and set according to trials performed by an engine test bed technician. Typical trials involved changing ERPM and engine load until met by surge or choke (or a target point) followed by updating the compressor geometry to maximize the compressor efficiency. Then, the technician would manually determine a set of steps. The variable geometry compressor would then use these steps during operation, mainly in an effort to avoid surge and choke.
Consequently, a need exists for better control strategies for variable geometry compressors. Various exemplary technologies disclosed herein aim to meet this need and/or other needs.